Clutch plate and method of making same



Sept. 1, 1942. E. v. J. TOWER CLUTCH PLATE AND METHOD. OF MAKING SAME Filed Jan. 5, 1941 INVENTOR. ELMER V.J TOWER.

ATTORNEYS Patented Sept. 1, 1942 Elmer V.-J. Tower, .Grand Ledge, Mich., assignor to The Accurate Parts Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application January 3, 1941, Serial No. 373,014

14 Claims.

.The present invention relates to a clutch plate and method of making it and 'has particular reference to a clutch plate wherein-a flange element extends radially from the hub proper and is a separate and'distinct part but a permanent adjunct'thereof. Such Ifianged hubs are found generally'. in two types of clutch plates. One type iis'exemplified :by .th construction wherein the radially extending :flange of the hub overlies the ".disk'body of the ,plate and is permanently at- .tached thereto 'by means of rivets passing .throughtboththejflange and the disk, The other .is' :the 'coil-springwushion-center type of 'con- :struction.

In the "fcoil-spring-cushion center type of clutch plate, :coiled compression springs are mountedbetween thehub element and the disk body of the plate. Th hubv element and the disk body-of the :plate are, of course, movably or rotatably mounted with respect toeach other and :the coil'springs vare'adapted to yieldably absorb the torque or force transmitted from the disk body to the hub so'that there is-produceda cushxioning, efiect. The 'hub elementof such a clutch plate has heretofore been constructed with an "integral flange having-radially extending arms or spokes whichabut against the end of the coil Springs. Such a construction has presented a major problem, both in fabrication .Of the hub element part and :in'the productionof the optimum desired physical characteristics and properties of the hub element with respect to the clutch plate "and other parts of .the clutch assembly.

The hub element must, of course, have'a fermalersplineyfittin upon the 'male spline of the driven shaftof the-clutch'assemb1y. Preferably, the :metal of this .hub portion proper, of the "clutch 'plate,-is't0 be made softerthan the metal "of the driven shaft, so that the latter'does not become unduly worn during use, so as to require frequent-replacement, it-being much more economical and convenient to replace the clutch plate rather than the driven shaft, since the former, in any event, is the moresusceptible to wear and depreciation during the normal life and use of the-clutch assembly. On the other hand, the flange portion of-the'hub element must possess a metallic hardness, in order to withstand the abutting contact with therivetsor coil springs, which hardness is substantially greater than the optimum desired hardness of the hub portion. Heretofore, when the hub portion and the flange portion of the hub element of such with each other, it Was necessary to sacrifice some of the desired relative. softness in the hub portion and some of the desired relative hardness 'inthe fiangeportion. Furthermore, such a hub element had to be machined from a single piece of parent stock. This involved, of course, a substantial amount of'waste metal, as Well asacom- :paratively high cost of fabrication,

.According to my present invention, however, the, hub portion and" the flange portion are initially fabricated in separate pieces which are subsequently permanently attached together. This permits the respective pieces to be'made of the desired'relativeihardness. Furthermore, the previous'lyrequired machining operation, with incidentiwasteofmaterial and high cost of production, are substantially reduced, and the flange portion itself'may be'fabricated from a much more economicalzmetal-shaping process, via, by stamping or pressing. -Furthermore,these-flange iportions;.can be made in varied thicknesses by using .a plurality of layers or laminations of more thano-nepiece.

My invention possesses a' further object and advantage whentap'plied to the construction of a clutch plate wherein a limit stop ring, carried by the disk body and disposed around the outer periphery-of the hub flange is employed. Such a limit stop ring construction is more fully shown and described in C. B. Spase U. S. Patent No. 2,124,013, granted July 19, 1938. According 'to the teachings of my invention, both the limit stop ring and the flange portion of the hub element may be formed from the same piece of parent stock, thus utilizing the large proportion of material heretofore discarded as Waste. Furthermore, this latter phase of my invention results in a more accurate and uniform control of the dimensionalspecifications of the limit stop ring and the'fiange portion of the hub, particularly With respect to .their interfitting dimen- .sional requirements.

clutch plates were made inone piece or integral "The foregoing objects and advantages, as well iasadditional ones, Will be pointed out in greater detail-as the following description proceeds.

Tothe accomplishment of the foregoing and .related ends, said invention, then, consists of the ..means and" elements hereinafter fullydescribed and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail certain structure em- :bodying theinventionand asapplied to a coilspringecushion-center clutch plate, such dis- ,closed elements-constituting, however, but one of various structural forms in which the principle of the invention may be used.

In said annexed drawing:

Fig, 1 is a cross-sectional View of a coilspringcushion center clutch plate constructed according to the principle of my invention; Fig. 2 is a plan view of the clutch plate shown in Fig. 1 and with a portion removed; Fig. 3 is a detailed sectional view, taken substantially along the line 33 of Fig. 2; Figs. 4 to '7, inclusive, are plan views illustrating the several steps of my new method for fabricating the flang portion of the hub element and the limit stOp ring from a single piece of parent stock; and Fig. 8 shows an alternative form of construction wherein the hub flange and stop ring are of laminated form.

Now referring more particularly to the drawing, there is shown therein a clutch plate having a disk body I to whose outer periphery the friction facing rings 3 and 4 are attached by means of the rivets 5. The disk body I has a central opening 6 in which th hub I is received. The hub I, in turn, has a female spline adapted to fit upon the male spline of the driven shaft of the clutch assembly (not shown).

A cover plate Or side plate 9 is attached to the disk body I by means of the rivets III. The cover plate 9 and the disk body I have aligned or registering sumps or pockets II and I2, respectively, in which the coil springs I3 are received, and against the ends of which these springs contact and abut. v The ends of the springs I3 also contact and abut against the sides of the radially projecting arms or spokes I4 on the hub flange portion I5. A limit stop ring I6 has integrally projecting lugs or bosses II, which circumferentially overlap the radial arms or spokes I4 and thus provide limit stops for limiting the amount of rotation of the flange I with respect to the disk body I.

Friction inserts I8, composed of cork, fibre, asbestos, or friction material, are inserted in holes 2| in the radial arms or spokes I4 or the holes 2| adjacent the inner periphery of the flange portion I5 and are adapted to bear against the contiguous flat surface portions of the disk body I and cover plate 9, thus producing a light, frictional engaging action between the hub portion and the disk portion of the clutch plate,'and in aid of the yieldable cushioning action of the coil springs I3. The hub I has a polygonally-shaped outer surface portion I9 (octagon-shaped, as shown in the drawing) upon which the flange I5 is press-fitted, so that the two parts are fixedly and permanently assembled together.

It will thus be seen that the hub I and the flange I5 are two separate pieces permanently assembled and attached together. Thus, the hub I may be fabricated from a relatively soft, low carbon steel which readily lends itself to machining operations, such as involved in the broaching of the internal or female spline 8 and the flange I5 may be stamped or pressed from a relatively harder, higher carbon steel; and the flange I5 may be separately heat-treated to improve its properties of hardness and toughness without detracting from the desired property of relative softness of the hub I, which would otherwise be the case if these two parts were fabricated from a single piece.

It will be obvious to those skilled in the art that although the previous example specifies low carbon steel and high carbon steel as the metallic stock from which the hub I and flange l5 may be fabricated, that other metals, including nonferrous metals, may be equivalently employed for the fabrication of these two parts.

The method of fabricating the stop ring I6 and the flange I5 from a single piece of stock is illustrated in Figs. 4 to 1, inclusive. Thus, a piece of flat or strip stock A is first operated upon to stamp or press out the stop ring form B and the preliminary or rough blank C for the flange, as shown in Fig. 4. Heretofore, the amount of metal represented by the portion C would have been just so much waste material, but this portion of material now serves as a blank for forming the hub flange I5. As shown in Fig. 6, the portions D are removed from the rough blank C to form the radial arms I4 and intervening recesses for the coil springs I3. The central, polygonal opening 25 is also stamped out to interflt with the correspondingly shaped outer surface portion I9 on the hub I. The holes 2| are stamped out to receive the inserts I8, of finished flange I5, as shown in Fig. "I. The finished stop ring I6 in which the rivet holes 22 have been added is shown in Fig. 5.

The above-described process of fabrication permits a very accurate and uniform control of the dimensional specification limits between the flange I5 and the stop ring I6. Thus, as indicated at E in Fig. 2, it will be seen that there is a fitting or clearance space between the outer ends of the spokes I4 and the inner periphery of the stop ring I6. Whenthe stock or rough blank C for the flange I5 is stamped or pressed from the same blank A from which the stop ring blank B is taken, it will be appreciated that this interfitting relationship of the flange I5 and the stop ring I6 must necessarily always be maintained. Heretofore, it was necessary to very carefully machine and check the dimensions of the flange on the hub to make sure that it would properly conform to dimensions interfltting with the dimensions of the inner periphery of the stop ring. The specification of closer tolerance limits for these dimensions are also made possible by reason of my process of fabrication, so that the clearance space E may be made quite close indeed, as compared to previous feasible manufacturing limits, and thus contributing in a greater measure to the precision of fit and alignment of the clutch plate parts.

The flange I5 or the stop ring I6, as shown in Figs. '7 and 5 respectively, may, of course, be subsequently heat-treated to improve their properties of hardness, toughness and strength, and before final assembly in the clutch plate.

It Will be apparent to those skilled in the art that equivalent means for permanently mounting or attaching the flange I5 upon the hub I may be employed, such as by using a different shape of interfitting surface, other than the octagonal shape shown in the drawing, or by other methods of attachment and press-fitting, such as brazing; or welding, all being equivalently available expedients within the scope of my invention.

In Fig. 8, I have shown a modified form of construction wherein the hub flange portion and the limit stop ring are themselves composed of a plurality of pieces, viz., are laminated. Thus, referring to Fig. 8, it will be seen that the hub flange portion is composed of the two radially parallel pieces or layers I5 and I5 and the stop ring is similarly composed of the two layers I6 and I6. This laminated construction possesses an advantage in that the thickness of the hub flange portion, particularly, may be more convenien-tly controlled in "commercial manufactur difierent hardness than that-of liaid hub', an'd ing practice. By building the' hubflange portion with a plurality of layers, it is possible to produce a substantial'number of thicknesses *forthe" hub flange and for-the -stopring-frdm--a relatively small number of sheetstocksizesr -In other words, it is not necessary to have on hand sheet stock for making" the hub flange {and-thestop ring, which is of a thickness-or size corresponding to each and every'size and thicknessof the flange and stop ring desired-to be'-made3-'- Furthermore, this laminated constructionimparts greater strength to the hubandclutchdisk assembly against *axially directed stresses. -'A

plurality of thicknesses of metal stock," or the laminated construction, "permits the clutch plate,

as a whole, to withstand forces-tending to-distort the body or disk portion-of the "clutchplate with respect to the hub portion.

It Willalso be understood that although I'ha'vespecifically illustrated and described-myinvention as applied "to a coil-spring-cushion-center type of clutch plate, that it may be equally Well and equivalently applied to that type of clutch plate construction in which the radially extending flange portion of the hub overlies and is rigidly or immovably attached to the disk body of the clutch plates, such as by rivets or similar fastening means. Such latter application of the invention being quite obvious to those skilled in the art, in view of the foregoing description, it has not been deemed necessary specifically to illustrate and describe it.

Other forms may be employed embodying the features of my invention instead of the one here explained, change being made in the form or construction, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed, whether produced by my preferred method or by others embodying steps equivalent to those stated in the following claims.

I, therefore, particularly point out and distinctly claim as my invention:

1. A hub element for a clutch plate having coil springs mounted between such element and its disk body, comprising a hub and a springabutting flange, said hub and said flange, respectively, having interfitting surface portions of non-circular cross-sectional shape being composed of metals of different hardness, the axial width of said interfitting portions being equal to the thickness of said flange.

2. A hub element for a clutch plate having coil springs mounted between such element and its disk body, comprising a hub and a spring-abutting flange, said hub and said flange being initially separate and having non-rotatable, interfltting axially extending surface portions of polygonal cross-sectional contour, said flange being subsequently press-fitted on said hub.

3. A clutch plate, comprising a hub, a flange on said hub, a disk body overlying one side of said flange and a side plate overlying the other side of said flange, radially extending arms on said flange, coil springs mounted between said radially extending arms, spring-receiving pockets for said coil springs in said disk body and in said side plate and friction inserts in said radial arms adapted to frictionally engage with said disk body and with said side plate.

4. In the method of making a clutch plate having a hub element, a disk body and coil springs mounted therebetween, the steps of machining a hub, stamping a spring-abutting flange thenpress-fittingsaidflange 'on said hub.-

5. In the method of making a clutch plate havinga hub -element; a disk body and coil springs mounted therebetween', the' stepsof ma I chining-a hub, providing a blank, forming a previously circumscribed by said ring.

6. 'Inthe method of making a clutch plate hav-' ing a hub element, a 'disk body and coil springs mounted therebetween, the steps of machining a hub; providing a blank, forming a limit stop ring from-a portion of said'bla'nkand forming-a spring -abutting-flange to fit on said hub 'from' the remaining portion of said blank previously circumscribed-by" said ring heat-treating said fla'nge'to a different hardne'ssthan'that of said hubfiand thenpress-fitting said flange-to said hub.--

7. A hub element for a clutch plate having coil springs mounted between such element and its disk body, comprising a hub and a spring-abutting flange, said hub and said flange being initially separate and having interfitting non-circular surface portions, said flange being subsequently, fixedly mounted on said hub, and said flange being composed of a plurality of radially parallel flat layers.

8. A clutch plate having a hub element and a disk body rotatably carried upon said hub element, the latter comprising a hub and a radially extending flange forming a part thereof and overlying said disk body, said hub and said flange, respectively having interfitting surface portions of non-circular cross-sectional shape and being composed of metals of different physical properties.

9. A clutch plate having a hub element and a disk body rotatably carried upon said hub element, the latter comprising a, hub and a radially extending flange forming a part thereof, said hub and said flange being initially separate, said flange being subsequently, fixedly mounted on said hub, an external, non-circular surface portion on said hub having an axial width equal to that of said flange, a complementary internal surface portion on said flange for non-rotatably fitting over said hub surface portion, and an external circular surface portion on said hub for rotatably fitting within said disk body.

10. A clutch plate having a hub element, a disk body having a circular opening for receiving said hub element, coil springs mounted between said hub element and said disk body, said hub element comprising a hub and a spring-abutting flange, said hub having an outer surface portion of polygonal cross-section, said flange having a central opening of similar cross-sectional shape and adapted to be tightly fitted on said outer hub surface.

11. A clutch plate having a hub element, a disk body having a circular opening for rotatably receiving said hub elements, coil springs mounted between said hub element and said disk body, said hub element comprising a hub and a spring-abutting flange, said hub and said flange non-rotatably fitted thereover, and a circular external surface portion on said hub for rotatably fitting with said circular opening in said disk body.

12. A clutch plate having a hub element, a disk body rotatably mounted on said hub element, coil springs mounted between said hub element and said disk body, said hub element comprising a hub and a spring-abutting flange overlying said disk body, said hub and said flange, respectively :being composed of metals of different physical 1 tral opening of similar cross-sectional shape and adapted to be tightly fitted on said outer hub surface, and another portion of the outer surface of said hub being circular to fit within said circular opening in said disk body.

14. A clutch plate having a hub element, a disk body rotatably mounted thereon, coil springs mounted between said hub element and said disk body, said hub element comprising a hub and a spring-abutting flange, said hub and said flange, respectively being composed of metals of different hardness, said hub having an outer surface portion of polygonal cross-section, and of an axial width equal to the thickness of said flange, said flange having a central opening of similar .crosssectional shape and adapted to be tightly fitted on said hub surface portion, said flange being composed of a plurality of radially parallel, fiat layers, and another outer surface portion of said hub of circular cross-section and adapted to fit within said disk body.

ELMER V. J. TOWER. 

